Flexible couplings include a driving member, a driven member and a flexible element transmitting torque from the driving member to the driven member. Such a flexible element is generally made up of a body of flexible material, e.g. rubber, and of a fabric insert. A flexible coupling further includes clamping means for clamping the flexible torque-transmitting element adjacent one or both of its rim zones to the driving and to the driven coupling members.
Flexible torque-transmitting elements may take various forms and shapes. In one type the flexible torque-transmitting element is generally in the shape of an automobil tire. Its rims are clamped to the driving member and to the driven member of the coupling, respectively.
In another type of flexible coupling one of a pair of coupling members has a relatively large diameter, and the other of said pair of coupling members has a relatively small diameter. Both coupling members are arranged in coaxial relation. They are tied together by a substantially angular resilient torque-transmitting element. The outer periphery of the torque-transmitting element is clampemd against a surface of the large diameter coupling member, and the inner periphery of the torque-transmitting element is clamped against a surface of the small diameter coupling member. In such couplings the rims of the resilient torque-transmitting element, particularly the radially inner rim thereof, are subjected to very large clamping pressures. The degree of compression to which the resilient material is subjected of which the torque-transmitting member is made results in serious drawbacks, and may ultimately result in total inoperativeness of the torque-transmitting element and, therefore, of the entire coupling.
Resilient materials such as rubber are subject to a certain degree of ageing. As a result of such ageing, the clamping pressure and the friction at the clamed rim of the torque-transmitting element decrease progressively and the torque that can be transmitted by the tonque-transmitting element decreases as the friction decreases. To maintain the required ability of torque-transmission the clamping screws must be re-adjusted, or tightened, from time to time. This may result in excessive compression of the torque-transmitting element, and in permanent deformation thereof as well as in the formation of cracks therein.
Various suggestions made heretofore to obviate these drawbacks had no significant results. One of these rather inoperative suggestions consists in encapsulating steel-reinforcements in the rims of torque-transmitting members, or imparting a certain geometry to the rims thereof, or providing friction-increasing layers thereon. In spite of these and other means for precluding progressive deterioration of the clamping rims of torque-transmitting elements of flexible couplings, it became necessary to progressively increase the diameters of flexible couplings as the torque to be transmitted increase.
It is, therefore, the primary object of the present invention to provide torque-transmitting elements for flexible couplings and flexible couplings, respectively, that have a relatively small diameter considering the torque they are capable of transmitting, which elements and couplings are not subject to damage as a result of the application of very high clamping pressures.